Wasatch Cache National Forest

In partnership with: The Friends of the Utah Avalanche Forecast Center, Utah Department of Public Safety Division of Comprehensive Emergency Management, Salt Lake County, and Utah State Parks

: http://www.avalanche.org/~uac/

Avalanche advisory

Friday, NOVEMBER 14, 2003 7:30 am

Good morning, this is Andrew McLean with the Forest Service Utah Avalanche Center with your avalanche and mountain weather advisory. Today is Friday, November 14, 2003, and it’s 7:30 a.m.

Avalanche Conditions:

The last two days have been very active. On Wednesday, a snowmobiler was buried 3’ deep on Logan Peak after triggering a slide at 9,700’. His friends dug him out OK. Yesterday, a skier triggered and was caught in slide in the East Bowl of Silver Fork after starting an avalanche on a 33 degree slope. The same skiers also triggered two other slides remotely from the ridge. In addition, a skier triggered two slides on Rocky Point in upper Little Cottonwood. In the Provo area, two skiers were caught in slide in the Aspen Grove area that broke out on a 32 degree slope. Both are OK and reported hearing natural releases in the area. The slides are breaking 12 – 18” deep and running full track. Collapsing and cracking are wide spread on northern aspects.

All of these slides occurred on a buried layer of frost or “surface hoar” that formed last weekend with a 12-18” soft slab on top of it. This is a very difficult layer to detect and causes fast, clean fractures. The surface hoar is widespread above 8,500’ especially on north facing slopes and avalanches are running on surprisingly flat slopes with angles as low as 32 degrees.

Patience is a virtue in the backountry right now. Surface hoar is notoriously persistent, pockety and difficult to detect. Surface hoar is fairly rare in Utah so you will likely notice unusual avalanches breaking lower on the slope than you expect and on very gentle slopes. You need to temper your early season enthusiasm by staying on low angle terrain, practicing safe travel techniques, doing slope cuts, going one at a time and using safe route finding. While the current snow is great for our long term outlook, it poses immediate short term concerns.

Current Conditions:

The storm totals are 16” in the Cottonwood Canyons with 10 - 12” falling in the last 24 hours and the snow amounts seem to be fairly evenly spread throughout the Wasatch Range, with most storm totals around a foot. The snow density varies quite a bit with elevation with denser, moist snow around the rain-snow line at 6,500’ and light, dry snow up high. There is also some graupel mixed in. Exposed sunny slopes have wind and sun crusts that are now buried. 8,000’ temperatures are around 28 degrees and ridge top winds have been 10-15 mph from the southwest.

Bottom Line (Salt Lake, Park City and Ogden area mountains):

The avalanche danger on northeast, north and northwest facing slopes above 8,500’ is HIGH. Below 8,500’ it is CONSIDERABLE with warm, damp to wet avalanches becoming a concern.

Provo area mountains: The avalanche danger in the Provo mountains is HIGH on slopes steeper than about 30 degrees. In these areas, human triggered avalanches are likely and natural avalanches probable. The danger in the Provo area mountains increases with elevation.

Mountain Weather:

A small area of high pressure will build this afternoon as an area of low pressure exits. Snow showers will taper off today with scattered clouds. On Saturday, unsettled weather with a chance of light snow is expected, followed by a moist low level air mass anticipated to arrive late Saturday night and starting to snow in earnest on Sunday with another 4-8” of snow expected.

General Information:

If you are getting into the backcountry, please give us a call and let us know what you’re seeing, especially if you trigger an avalanche. You can leave a message at 524-5304 or 1-800-662-4140. Or you can e-mail an observation to uac@avalanche .org, or you can fax an observation to 801-524-6301.

The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur.

Bruce Tremper will update this advisory Saturday morning.

Thanks for calling!

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For more detailed weather information go to our Mountain Weather Advisory

National Weather Service - Salt Lake City - Snow.

For an explanation of avalanche danger ratings:

http://www.avalanche.org/usdanger.htm